Fuel cells are well known and are commonly used to produce electrical current from hydrogen containing reducing fluid fuel and oxygen containing oxidant reactant streams to power electrical apparatus. Fuel cells are typically arranged in a cell stack assembly having a plurality of fuel cells arranged with common manifolds and other components such as a coolant loop, fuel reformer, controller and valves, etc. to form a fuel cell power plant. In such a fuel cell power plant of the prior art, it is well known that fuel is produced by the fuel reformer and the resulting hydrogen-rich fuel is referred to as a reformate fuel that flows from the reformer through a fuel inlet line into anode flow fields of the fuel cells. An oxygen-rich reactant simultaneously flows through cathode flow fields of the fuel cells to produce electricity.
Fuel cell power plants are known to provide electricity for differing types of apparatus. For example, many efforts are being undertaken to produce a fuel cell power plant utilizing “proton exchange membrane” (PEM) fuel cells to power transportation vehicles. Fuel cells utilizing phosphoric acid electrolytes are also known to power stationary electricity generating plants. A fuel cell power plant may also serve a valuable role as a back-up electricity generator for apparatus requiring electricity that are considered to be of extremely high value to society. For example, telecommunication stations provide very valuable services in maintaining consistent communication between government agencies, businesses, and individuals. At a time of emergency, such as a natural disaster, it is critically important that telecommunication stations remain functioning despite a loss of electrical power to the stations that may result, for example, due to a failure of an electrical power distribution grid.
Typical back-up power for critical systems have relied upon internal combustion engine powered generators and/or batteries that are costly to maintain, frequently operate for only short durations, and can be unreliable.
Fuel cell power plants have the potential to become efficient emergency back-up electricity generators. However, use of a fuel cell power plant as a back-up generator gives rise to many difficulties, such as a significant cost of storing large quantities of pure hydrogen. Fuel cells run optimally on fuel that is essentially pure hydrogen gas. Unfortunately, pure hydrogen gas must be compressed under very high pressure to store an adequate volume of the gas to operate a fuel cell power plant for more than several hours. Such high pressure storage of hydrogen gas involves substantial cost and safety concerns. Having a fuel reformer within the fuel cell power plant provides an opportunity to store and utilize readily available fuels such as natural gas or LPG, etc., that are easier to acquire, transport and store. However, a fuel reformer typically requires a long start-up time of about thirty minutes to generate adequate heat, steam and other prerequisites to reform a fuel into essentially hydrogen-rich gas.
Therefore, there is a need for a fuel cell power plant utilizing a reformate fuel that may rapidly start-up to serve as a reliable, efficient, emergency back-up electricity generator. There is also a need for a reformate-fuel powered fuel cell power plant that may quickly increase electricity output to meet sudden increases in demand for electricity by a critical load.